What did "containment " mean in the context of the Cold War policy

Containment was a United States policy using numerous strategies to prevent the spread of communism abroad. A component of the Cold War, this policy was a response to a series of moves by the Soviet Union to enlarge its communist sphere of influence in Eastern Europe, China, Korea, and Vietnam.

In the context of the Cold War, "containment" was a US strategy, wherein communism would be "contained" in the East. It didn't want communism to spread from the USSR to East European countries, China, Korea, and Vietnam. It was one of the most basic strategies in the Cold War.